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Biopolymers-Based Nanocomposites: Functions and Applications
Published in Shiji Mathew, E.K. Radhakrishnan, Nano-Innovations in Food Packaging, 2023
Alka Yadav, Gauravi Agarkar, Luiza Helena Da Silva Martins, Mahendra Rai
For ocular drug delivery, topical administration has been the most preferred route as it is painless, noninvasive and reaches anterior tissues as well as back-of-the-eye tissues (Cholkar et al., 2012; Agarwal and Rupen-thal, 2016). But effective delivering a topical drug has major challenge of low ocular bioavailability that can be enhanced by expanding the retention time in precorneal area and elevating the permeability of drugs across the ocular tissues (Barar et al., 2016). Xu et al. (2018) have developed functional intercalated nanocomposites based on chitosan-glutathione-glycyl-sarcosine (CG-GS) and layered double hydroxides (LDH) as ocular drug carriers to treat mid-posterior diseases. Glycylsarcosine (GS), an active target ligand of peptide transporter-1 (PepT-1), distinctively connects with PepT-1 present on the cornea and leads the nanoparticles to the targeted site. In the experiments on rabbits, these CG-GS-LDH nanocomposites showed sustained release, enhanced bio-adhesion, longer precorneal retention, higher distribution of fluorescence probe/model drug, and also exhibited increased cellular uptake in comparison to pure drug solution. Further, an ocular irritation study and cytotoxicity testing had revealed good biocompatibility and no significant irritant effects.
CNT-Based Bio-Nanocomposite as Electrochemical Sensors
Published in Mahmood Aliofkhazraei, Advances in Nanostructured Composites, 2019
S.K. Suja, G. Jayanthi Kalaivani
Creatinine amidohydrolase (creatininase) obtained from Pseudomonas putida has a molecular weight of 1,75,000 by ultracentrifugal analysis and the molecular weight of the subunit estimated by SDS-polyacrylamide gel electrophoresis was 23,000, suggesting that the enzyme is composed of eight monomeric subunits. The enzyme was found to contain about one gram atom of zinc per monomer subunit and it catalyzes the hydrolysis of creatinine to creatine (Rikitake et al. 1979). Creatine amidinohydrolase (creatinase) is a homodimer with the subunit molecular weight of approximately 45 kDa. The two active sites of this protein are at the interface of the monomers being shared by each monomer and only the dimer is active. The enzyme catalyzes the hydrolysis of creatine (Figure 9). Sarcosine oxidase from the Arthrobacter sp. is a monomer with a molecular weight of 43 kDa. The monomeric sarcosine oxidases are flavine proteins that contain 1 mol of flavine adenine dinucleotide (FAD) that is covalently linked to the enzyme by a cysteine residue. It catalyzes the oxidative demethylation of sarcosine (N-methylglycine) and forms equimolar amounts of formaldehyde, glycine, and hydrogen peroxide (Berberich et al. 2005a, Berberich et al. 2005b). The complexity of the three-enzyme system makes the process of commercialization slow.
Inorganic Chemical Pollutants
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
Plasma tHcys was significantly inversely associated with %MMA in males, and its estimated correlation with %DMA was positive, although not statistically significant among both males and females. These associations are opposite of those in adults. Although additional studies will be required to clarify the mechanism underlying these observations, the findings raise the question of whether there may be differences in the fundamental regulation of one-carbon metabolism between children and adults. Theoretically, one would expect overall upregulation of one-carbon metabolism during periods of rapid growth to meet the high demands for protein and DNA synthesis. In rats and rabbits, glycine-N-methyltransferase (GNMT) activity levels are very low at birth and increase continuously with age.782 Since GNMT, which catalyzes the nonessential methylation of glycine to sarcosine, competes for SAM and generates SAH, lower activity during periods of rapid growth may be one mechanism whereby increased requirements for SAM during growth and development are achieved. Whether similar developmental changes occur in humans is unknown.
Metabolomics approach to biomarkers of dry eye disease using 1H-NMR in rats
Published in Journal of Toxicology and Environmental Health, Part A, 2021
Jung Dae Lee, Hyang Yeon Kim, Jin Ju Park, Soo Bean Oh, Hyeyoon Goo, Kyong Jin Cho, Suhkmann Kim, Kyu-Bong Kim
The global profiling data showed a clear separation of clustering between control and DED groups (under scopolamine and desiccant stress conditions) on the par-scale of PCA and OPLS-DA models (Figure 6C,D). A total of 88 endogenous metabolites were identified using Chenomx NMR Suite ver. 8.3 (Chenomx Inc., Edmonton, Alberta, Canada) in urine samples of control and DED groups (Supplementary Table 1). PCA and OPLS-DA score plots in urinary target profiling exhibited clear discrimination of clustering between groups (Figure 8). VIP demonstrated the sorting of endogenous metabolites in the order of contribution to separation of clustering. Significant metabolites were selected according to a VIP value of more than 1, which determined meaningfully important metabolites (Figure 8C). Further, the 26 urinary metabolites selected from the DED group were as follows: phenylalanine, phenylacetate, pantothenate, glycine, succinate, methanol, valine, propylene glycol, histidine, threonine, lactate, acetate, o-cresol, isoeugenol, N6-acetyllysine, trimethylamine, taurine, cis-aconitate, N,N-dimethylglycine, N-acetylglucosamine, thymol, leucine, melatonin, malonate, N-methylhydantoin, and sarcosine. Among the metabolites, phenylalanine, phenylacetate, pantothenate, glycine, succinate, methanol, valine, propylene glycol, histidine, threonine, lactate, and acetate exhibited significant differences.
Effect of blanching on volatile compounds and structural aspects of Cordyceps militaris dried by microwave-assisted pulse-spouted bed freeze-drying (MPSFD)
Published in Drying Technology, 2019
Xiao-fei Wu, Min Zhang, Bhesh Bhandari, Zhongqin Li
A total of eight esters were identified in dried C. militaris. In general, esters are beneficial to the positive fruity flavor of food products. They were associated with the esterification of alcohols and free fatty acids. Compared with other blanching treatments, blanching at 50°C for 15 min exhibited a higher ester contents. Results demonstrated that a long time and high temperature blanching was not good to the retention of esters. 2-(Aminooxy)-butanoic acid, acetic acid, 2-(aminooxy)-propanoic acid, and nonanoic acid were the four acids found in dried C. militaris. Among these acids, acetic acid and nonanoic acid were not detected in untreated samples. N-methylglycine (sarcosine) is an intermediate and byproduct in glycine synthesis and degradation.[30] The appearance of this compound indicated the existence of sarcosine in dried C. militaris. 2-Pentyl-furan was only identified in untreated C. militaris and samples blanched at 50°C for 60 min with low concentrations. Furans generally relate to the caramel-like odor of heated carbohydrates.[31] Benzothiazole belongs to the sulfur-containing heterocyclic volatile compound, contributing to the grilled and roasted flavors of dried C. militaris. Benzothiazole was only detected in samples blanched at 50°C for 60 min and at 100°C within 60 s. This compound arises from the Maillard reaction during heating process.[32]
Epigenetic modifications associated with pathophysiological effects of lead exposure
Published in Journal of Environmental Science and Health, Part C, 2019
Madiha Khalid, Mohammad Abdollahi
Apoptosis is triggered via the cascading action of several enzymes under the control of complex signaling pathways. Closely related apoptotic genes belong to Bcl-2 families such as Bax and Bad genes, i.e., Bcl-2 is an associated agonist of cell death, while Bcl-2/w/xl, the apoptosis regulator Mcl-1, and the anti-apoptotic protein NR-13 oppose apoptosis.275,276 Pb triggers apoptosis via inducing oxidative stress. It induces oxidative stress by decreasing the mRNA expression level of glycometabolism enzymes,277,278 MDA-mediated lipid peroxidation,279,280 and by decreasing SOD and GSH-Px activity.281,282 Oxidative stress leads to mitochondrial dysfunction which ultimately triggers apoptosis,283 characterized by abnormal activity of Bax, p53, mitochondrial cytochrome-c (Cyt-c), caspase-3 and caspase-981,284 (Figure 5). Studies with chicken liver demonstrated an increased number of apoptotic cells (P < 0.05) as a result of 350 mg/L Pb exposure. Reduced levels of metabolic enzymes were observed, including Na+-K+-ATPase, Ca2+-ATPase, Mg2+-ATPase, and ROS scavenging enzymes, including superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) (P < 0.05). The levels of iNOS, MDA, and NO (P < 0.05) were significantly increased, suggesting Pb-induced imbalance among metabolic and ROS scavenging enzymes. Decreased mRNA levels for hexokinase (HK2), sarcosine dehydrogenase (SDH), plucked (PK), and pyruvate dehydrogenase complex component X (PDHX) were observed (P < 0.05). Pb exposure caused decreased mRNA expression levels of mitochondrial fission and fusion genes and their corresponding proteins (P < 0.05) such as fission-mitochondrial 1 (Fis1), dynamin-related protein 1 (Drp1), OPA1 mitochondrial dynamin-like GTPase (OPA1), and mitofusin 1/2 (Mfn1/2). The mRNA levels of some apoptotic genes and their corresponding proteins levels were increased, such as p53, Cyt-c, Bax, caspase-3, and caspase-9 (P < 0.05) except Bcl-2, suggesting Pb-induced apoptosis due to imbalance of different pro-apoptotic and anti-apoptotic factors as displayed by ruptured cells, swelling, chromosome condensation, cell body shrinkage, and mitochondrial vacuolization in the liver.285 Similarly, many studies reported Pb-induced cytoplasmic swelling, nuclear vesiculation, hepatic cellular damage, necrosis, and histopathological alterations in the liver.286–288